The invention relates generally to a mechanical plug device and, particularly, to a well monitor plug device for sealing the exposed top of a subwell casing.
Environmental concerns relating to the integrity of underground storage tanks for containing various chemical products, such as petroleum products and the like, have resulted in federal and state laws which require the continuous monitoring of storage systems. For example, one monitoring system involves the placement of a non-permeable liner below and around an underground storage tank to contain possible leakage. A number of perforated subwell casings are placed within the confines of the lined area and by monitoring these casings the storage tank can periodically be sampled for leakage to, thereby, check its integrity.
Although various plug and sealing devices have been proposed and utilized for sealing the subwell casings of these monitoring systems, problems remain with providing an effective plug device which will ensure tamper resistance of the casing during periods of non-use and which will provide quick and efficient access to the casing for testing purposes. For example, existing plug devices used in the construction and plumbing industries have been used for sealing these subwell casings. However, these devices typically do not offer tamper resistance, nor do they provide an easy and efficient means to monitor the well without the removal of the entire plug device. The shortcomings and problems of these prior art devices have caused plug device parts to fall into the subwell casings and have caused these casings to be mistaken for tank fill pipes. It is an object of this invention to provide an effective well monitor plug device for sealing subwell casings.
The well monitor plug device of the present invention has structure which provides a unitary plug which provides for the tamper resistant sealing of subwell casings. The plug device of the invention permits the effective sealing of the subwell casing and provides means to effectively lock the device during periods of non-use and efficient means to permit the periodic sampling of the subwell.